1. Technical Field
The present invention relates to an image forming apparatus utilizing an electro-photographic system, such as a copying machine, a printer, a facsimile, a multifunction machine of these functions, and the like.
2. Related Art
In an image forming apparatus such as a printer and a copying machine, cut sheets (papers, flat papers), which can be continuously fed are generally used as recording medium on which an image is formed. For the purpose of restraining so-called multifeeding by which a plurality of sheets are fed in tight contact, when the sheets are fed out one by one from a sheet tray, copying sheets and high quality sheets to be used in the image forming apparatus are designated by respective manufacturers of the copying machines. The sheets designated by the manufacturers have relatively low surface smoothness, and adhesiveness between the sheets is weak.
However, in recent years, it has become more and more required that the sheets of various types including those having high surface smoothness are conveyed, as diversity of the recording medium increases. Particularly, with progress of coloring technique, it has been highly required to convey, in a machine of the same type, coated paper having enhanced whiteness and gloss, an OHP sheet, tracing paper and the like and further, thick paper having especially high basis weight.